Rearrangement during attempted allylation of 2α-Bromo-5α-cholestan-3-one

Treatment of 2α-bromo-5α-cholestan-3-one with zinc and allyl bromide in benzene-dimethyl sulphoxide yields, amongst other products, the ring-A contracted compounds 2α-(but-3?-en-1?-oyl)-A-nor-5α-cholestane (3) and 2α-[4?-(4?-hydroxyhepta-1?,6?-dienyl)]-A-nor-5α-cholestane (5).*

Quantitation of the normal Frank and McFee-Parungao orthogonal electrocardiogram in the adolescent

A detailed linear, circular and spherical quantitation of the Frank and McFee-Parungao orthogonal electrocardiograms of 166 adolescents is presented.

There are significant differences between pubescent males and females: (1) QRS and T magnitudes in the male are greater than in the female. (2) The difference in magnitudes is greater at age 11-15 than at age 16-19, presumably because females reach puberty earlier. (3) The differences in magnitudes are on the X and Z axes but not the Y axis. (4) Males achieve their maximal posterior QRS orientation sooner than females and are more superior as it occurs. (5) The female's T vector is less anterior than the male's. (6) The angular deviation of T from QRS is less in females than males for the horizontal and sagittal planes.

There are significant differences between the two lead systems: (1) The McFee-Parungao's voltages are greater than those of the Frank system. (2) On the X axis, the Frank leftward vector is 62% of the McFee, but the terminal rightward vector is 85% of the McFee. (3) On the Y axis, the Frank inferior vector is 76% of the McFee, but initial superior is 90% and the terminal superior 62% of the McFee. (4) On the X axis, 25% is terminally to the right in the Frank, but only 15% in the McFee. (5) The Frank system is oriented slightly more posterior than the McFee, though the T vectors are not oriented differently.

There is no evidence that the spatial QRS and T orientations are related to each other.

A feedback mechanism responsible for fixed coupling in parasystole

The ventricles of open-chest anesthetized dogs were stimulated at a constant frequency to simulate ventricular parasystole. When the stimulation frequency was approximately half the spontaneous discharge frequency of the sinoatrial node, the natural pacemaker became synchronized with the artificial pacemaker. During such entrainment, the parasystolic rhythm resembled bigeminy with fixed coupling. Numerous instances of concealed bigeminy were also observed. Characteristic changes in arterial blood pressure always accompanied the repetitive ectopic beats, and these changes in blood pressure, acting mainly through the baroreceptor reflexes, were principally responsible for the synchronization. When the cardiac autonomic neural pathways were interrupted, synchronization usually could not be achieved. The biological feedback control system producing synchronization may be represented as follows. (1) The difference in timing between the firings of the sinoatrial node and the ectopic focus is the coupling interval. (2) This interval is a determinant of the stroke volumes of the premature and the postextrasystolic beats. (3) The stroke volumes affect the arterial blood pressure. (4) The level of blood pressure influences the neural activity in the baroreceptor reflex arc. (5) This activity in turn alters the frequency of the sinoatrial node. (6) Finally, sinoatrial nodal frequency affects the coupling interval to close the feedback loop.